water Flashcards
Describe the bond between H and O atoms.
It is a weak hydrogen bond. Lots of hydrogen bonds in water make it stable although it doesn’t require much energy to break them.
What is high specific heat capacity?
It means water doesn’t heat up easily. It takes a lot of energy just to heat it 1C. Also it can lose a lot of energy before it falls in temperature.
Why is water dipolar and what does it mean?
It means water has both a positive and negative charge and it happens because the oxygen has a greater affinity for electrons n therefore has a slightly negative charge. The hydrogen atom has a slightly positive charge because of this.
Why do salts dissolve in water?
The opposite charges on each compound attract each other and so the negative oxygen pulls the positive Na as the positive hydrogen pulls away the negative Cl.
Why is it helpful that water is a good solvent?
Substances such as glucose, amino acids, fats, vitamins etc need to be transported around in a solution.
Why is the high specific heat capacity helpful to enzymes?
It ensures the temperature is stable to prevent the enzyme from denaturing etc.
Why is water essential to transport?
All movement in phloem (sugars, amino acids, hormones) occurs in solution.
All transport fluids (cytoplasm, blood, plasma, tissue fluid) are water-based.
Why is water essential to chemical reactions?
Thermal stability and being a good solvent make water ideal for reactions.
Water also acts as a reactant (Hydrolytic reactions eg. digestive enzymes).
Why is water essential for controlling temperature?
High specific heat capacity; essential for maintaining a constant temperature (eg body temp. enzyme conditions).
The hydrogen bonds makes it hard for water molecules to evaporate so when it does it releases a lot of energy. This is involved in cooling mechanisms.
Why is water essential for support?
Turgidity is essential to plant cells.
This helps in maintaining maximum leaf surface area (light absorption, photosynthesis) and in maintaining aerial parts of the plant to therefore maximise seed dispersal/pollination.
For aquatic organisms, water provides buoyancy.
Why is water essential to movement?
Nastic movements (do not involve growth in a particular direction as a response to a directional stimulus) depend on the (osmotic) flow of water into tissues. Some animals (earthworms and leeches) use their hydroskeleton to move around.
Why is water essential to reproduction?
Water brings the male and female gametes together during fertilisation.
(In mammals) the foetus develops in a water filled sac which provides physical and thermal stability).
